Our overall objective is to elucidate the mechanisms that regulate gene expression at the level of transcription in mammalian cell, and, in particular, the mechanisms that regulate alpha-fetoprotein (AFP) gene transcription during ontogenesis and hepatocarcinogenesis. We attempt to determine if the differentiation and hepatocarcinogenesis involves a change in the transcriptional activity in the cells, and to identify the nuclear macromolecules that affect AFP gene transcription. In this project, we also study the effects of hormones on AFP synthesis in developing rat liver with the purpose of creating a new approach to the study of AFP regulation and its relationship to liver cell differentiation and malignant transformation.